Check My Math: Adding Disodium EDTA to Your HydroBuddy Nutrient Recipe?

[ExNavyInSTL]

I would like someone who makes their own fertilizer to check my math.

I've learned Hydro Buddy and I have created my "ideal" nutrient recipe (in theory).

However, I want to make sure I understand the formula for adding Disodium EDTA to chelate my Fe, Mn, Zn & Cu.

From what I have extrapolated from Dr. Daniel Fernandez's various comments at the bottom of his DIY Nutrient videos on YouTube, it goes something like this.

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1) After Final Recipe has been chosen and concentrated (i.e. 1 Liter @ 200:1),
you take the millimolar concentration amount and change 'ppm' to mM' on "Main Page."

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After Switching to 'mM," it looks like this:

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2) Once you have the millimolar concentration (numbers above in yellow boxes), you add up the 4 numbers:

Fe: 4.298E-02
Mn: 9.101E-03
Zn: 3.363E-03
Cu: 4.721E-03
-------------------
= 6.02E-02 (0.0602)

Actually, it is: 0.060165

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3) Once you establish this number:

Multiply by the concentration Amount (200:1). It would be multiplied by 100 if 100:1.

0.060165 x 200
= 12.033

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4) Next he likes to add 20 or 25% for safety.

12.033 x 1.25
=15.041

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5) Now you take your "safe" total and multiply by the molar mass of Disodium EDTA (336.21) for your grams:

15.0412 x 0.33621

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That leaves you with the grams required.

However, the number isn't necessarily complete.
In this case, it is, but if the amount was 0.5 liter it would be different.

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For the Final Number, Multiply grams by the volume of concentration (1 Liter):

5.06 x 1.00
= 5.06 grams

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If it were for 0.5 liters, then it would be :

5.06 x 0.5
=2.53 grams

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Have I interpreted the formula correctly?

 

[ExNavyInSTL]

I just hope I put it in a form so that people who do know what I am talking about can make sense of it.

Here is a little more background. The first is a screenshot from me. His answer had me going back to my college chemistry classes (I got Ds in both).

I was suddenly using a periodic table to get molar mass, then going to calculators for molar concentration, etc.

Then in another video's comments, he put it in a way that made the lightbulb go on in my head. HydroBuddy already had molar concentration inside. You just had to change one setting.

From that answer, I was able to formulate the question above (I hope).

Another Answer:

 

[Dr.Mantis]

So,

The way I do it is pretty similar, but you need to keep a few things in mind. My overall process is:

1.Convert ppm to molar
2. Multiple molar to moles by (Molarity x liters = moles)
3. Multiple total moles of each by the valence of the cation. Example: Fe2+ will need less than Fe3+.
4. Sum the molar equivalents and multiple by the molecular mass of you chelating agent.

A few things to keep in mind: the oxidation state of your cations. The hydration status of your salts. The chelation level you are going for. For example, edta is tetradentate and can form chelates of multiple denticity with participating metal ions.

I don’t use edta so I can’t comment on that, but I do use glycine and citric acid for my metal ions. It’s not as “robust” as edta, but the plants can easily metabolize all of it, and there is no sodium.

 

[Tomatoesonly]

Ahhh yes.. a post that shows I don't know sht about actual nutrient mixing.

 

[Dr.Mantis]

One more thing when reading your post. I don’t quite fully understand the “concentration factor” box in hydrobyddy. It’s easier for me to go via “ how much nutrients at the desired ppm do I want to make for x liters of final nutrient”. Then, when mixing things up for say 100L or 1000l, it’s very easy to do volumetric dosing. A hypothetical would be 25g of materials for my micros for 100l. Then, all I would need to do is dissolve the material in enough water to make 100ml, and simply add one ml of stock per liter of final solution. I think that’s the idea here with the “concentration factor” but I have mostly done everything in an excel sheet, so I get confused when I can’t see the calculations.

One final thing, in your final steps when you have calculated the milimoles of material you need, it should be converted to moles before multiplying by the molecular weight. If you numbers look goofy, you can do quick sanity tests by multiplying the element % of you salt x the weight/total volume. If that is way off, there is probably an issue somewhere in the math.

 

[ExNavyInSTL]

Dr. Mantis:

I'm sailing in unchartered waters so when I reply I could be comparing my oranges to your apples.

I have a worksheet (template) I am still putting together. I'll post it so that my math is a tad clearer (maybe). : )

One more thing when reading your post. I don’t quite fully understand the “concentration factor” box in hydrobyddy. It’s easier for me to go via “ how much nutrients at the desired ppm do I want to make for x liters of final nutrient”. Then, when mixing things up for say 100L or 1000l, it’s very easy to do volumetric dosing. A hypothetical would be 25g of materials for my micros for 100l. Then, all I would need to do is dissolve the material in enough water to make 100ml, and simply add one ml of stock per liter of final solution. I think that’s the idea here with the “concentration factor” but I have mostly done everything in an excel sheet, so I get confused when I can’t see the calculations.

One final thing, in your final steps when you have calculated the milimoles of material you need, it should be converted to moles before multiplying by the molecular weight. If you numbers look goofy, you can do quick sanity tests by multiplying the element % of you salt x the weight/total volume. If that is way off, there is probably an issue somewhere in the math.

 

[ExNavyInSTL]

One more thing ... these are the videos I have watched over and over trying to make sense of all this.

It was Dr. Daniel Fernandez who piqued my interest in DIY. He is the creator of HydroBuddy and the owner of "Science in Hydroponics."

The first one is the main video, the one I asked the questions on and he responded. But I gathered bits and pieces from all 3.

Make Your Own Master Blend From Raw Salts

Hydroponic Nutrients (No Micro Blend)

Large Scale Stock Solutions

What really brought me over to the DIY (nutes) side was this video by Dr. Bernstein (senior research scientist and head, Cannabis Physiology and Agronomy Lab, Volcani Center, Ministry of Agriculture, Israel).

In this video lecture for Cornell University, I learned things that were counter to everything I read on forums about Veg versus Flower nutrition.

Here's the gist of what her experiments proved.

Nitrogen (elemental): No need for more than 160 ppm in Veg or Flower

Phosphorus (elemental): No more than 30 ppm in Veg or Flower. Although it has a wide forgiving range (15 - 90), but no real gain comes from going above 30.

Potassium (elemental): No more than 100 ppm in Veg or Flower. Above 100 - 175 are also safe zones you just don't gain anything.

Magnesium (elemental): 30 - 40 ppm in Veg and in Flower. Friendly range of 35 - 140 ppm, but you are damaging the quality of the end product.

This is really an amazing lecture if you have the time or nerd out on this sort of stuff. She is why I call this Israeli Mix. You have to give and take a little because we also use combination elements like in Calcium Nitrate. I went higher on the Mg because I wanted it to be closer to 1/2 of Ca.

Nirit Bernstein: The power of nutrient management for optimizing Cannabis yield quantity and quality

 

[Tomatoesonly]

Here's the gist of what her experiments proved.

Nitrogen (elemental): No need for more than 160 ppm in Veg or Flower

Phosphorus (elemental): No more than 30 ppm in Veg or Flower. Although it has a wide forgiving range (15 - 90), but no real gain comes from going above 30.

Potassium (elemental): No more than 100 ppm in Veg or Flower. Above 100 - 175 are also safe zones you just don't gain anything.

Magnesium (elemental): 30 - 40 ppm in Veg and in Flower. Friendly range of 35 - 140 ppm, but you are damaging the quality of the end product.

This is really an amazing lecture if you have the time or nerd out on this sort of stuff. She is why I call this Israeli Mix. You have to give and take a little because we also use combination elements like in Calcium Nitrate. I went higher on the Mg because I wanted it to be closer to 1/2 of Ca.

Nirit Bernstein: The power of nutrient management for optimizing Cannabis yield quantity and quality

Very interesting. It's so strange that two University level scientists studying basically the same thing... can't agree. Here is a study I posted about in another thread. In this article, NPK seems to be 195-60-200 as optimal

Frontiers | Optimisation of Nitrogen, Phosphorus, and Potassium for Soilless Production of Cannabis sativa in the Flowering Stage Using Response Surface Analysis

Following legalisation, cannabis has quickly become an important horticultural crop in Canada and increasingly so in other parts of the world. However, due t...

www.frontiersin.org

 

[ExNavyInSTL]

They did allow for a generous range to fiddle with, but they do show when the differences matter.

Sometimes creating more bio-mass is what happens with the extra nutrients, but they don't do much for more flower mass.

The funny part is that the highest THC and other cannabinoids were at their peak if they were practically starved the whole time.

Sure, the plants look like shit, but for those seeking more THC and more terpenes, you gotta make them hungry and ugly. : )

Another interesting thing from her lecture is how Humics had a negative effect.

She even covers how feeding them in certain ways (differently) enhances or depresses certain cannabinoids. Like Pheno Hunting, you can go Terp Hunting, if you have a favorite.

What is surprising is their study MythBusts the claim that you have to add more P & K as you go into flower.

All those Bloom nutes might just be Snake Oil?

They are working on more of the nutrients. I am interested to see what is a sweet spot for calcium ... and if you really need about half of the Ca amount for the Mg.

Very interesting. It's so strange that two University level scientists studying basically the same thing... can't agree. Here is a study I posted about in another thread. In this article, NPK seems to be 195-60-200 as optimal

Frontiers | Optimisation of Nitrogen, Phosphorus, and Potassium for Soilless Production of Cannabis sativa in the Flowering Stage Using Response Surface Analysis

Following legalisation, cannabis has quickly become an important horticultural crop in Canada and increasingly so in other parts of the world. However, due t...

www.frontiersin.org

 

[Tomatoesonly]

They did allow for a generous range to fiddle with, but they do show when the differences matter.

Sometimes creating more bio-mass is what happens with the extra nutrients, but they don't do much for more flower mass.

The funny part is that the highest THC and other cannabinoids were at their peak if they were practically starved the whole time.

Sure, the plants look like shit, but for those seeking more THC and more terpenes, you gotta make them hungry and ugly. : )

Another interesting thing from her lecture is how Humics had a negative effect.

She even covers how feeding them in certain ways (differently) enhances or depresses certain cannabinoids. Like Pheno Hunting, you can go Terp Hunting, if you have a favorite.

What is surprising is their study MythBusts the claim that you have to add more P & K as you go into flower.

All those Bloom nutes might just be Snake Oil?

They are working on more of the nutrients. I am interested to see what is a sweet spot for calcium ... and if you really need about half of the Ca amount for the Mg.

That's not too surprising, as it appears that a plant has a certain amount of THC it can produce and if the buds are small they get loaded to the gills and if the buds are large, the concentration per gram goes down.

Edit.. I'm getting through that video. Maybe this is explained, but you don't see what happens as the other 3 nutes are mixed. Meaning, yeah you have 5 K concentrations, but they don't explain the concentrations of the other nutes. Are they running max N with max K and P or ?

 

[ExNavyInSTL]

All this video covers is N,P,K and Mg.

That's not too surprising, as it appears that a plant has a certain amount of THC it can produce and if the buds are small they get loaded to the gills and if the buds are large, the concentration per gram goes down.

Edit.. I'm getting through that video. Maybe this is explained, but you don't see what happens as the other 3 nutes are mixed. Meaning, yeah you have 5 K concentrations, but they don't explain the concentrations of the other nutes. Are they running max N with max K and P or ?

 

[Tomatoesonly]

All this video covers is N,P,K and Mg.

Yeah I get that. What I'm saying is they are doing experiments in just one element at a time without disclosing what ANY other element levels were. While testing Nitrogen... again.. what were the P, K, and Mg levels?

 

[ExNavyInSTL]

Sorry, I wasn't sure how far into the video you were when you added the edit.

I don't think they have published the final information yet. All I can find is the webinar.

However, I have looked over quite a few of their studies and they are usually pretty comprehensive
once in a peer-review format.

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For example, in a study of hers titled:

Impact of N, P, K, and Humic Acid Supplementation on the Chemical Profile of Medical Cannabis (Cannabis sativa L)"​

They list the varied testing conditions as well as the control.

Example: The plants were exposed to three enhanced nutrition treatments, compared to a commercial [control] treatment.

The enhanced nutrition treatments received the control treatment with the addition of either humic acids [+HA]; enhanced P fertilization [+P]; or enhanced NPK treatment [+NPK].

The fertilizers were supplied by fertigation, i.e., dissolved in the irrigation solution at each irrigation event at concentrations of:

65 ppm N (with 1:2 ratio of NH4+ / NO3–)
40 ppm P2O5 (17 ppm P), and
108 ppm K2O (90 ppm K).

Micronutrients were supplied chelated with EDTA at concentrations of:

0.4 ppm Fe,
0.2 ppm Mn, and
0.06 ppm Zn.

Fertilization was conducted from pre-mixed (final) solutions.

For the [+HA] treatment, humic acids were added daily, 2 h after the last fertilization each day, as a liquid humic acid solution, 200 ml/pot of a 1:10 (W/W) dilution of a commercial product containing 12% humic acid (Uptake 12, Lidorr chemicals LTD, Ramat Hasharon, Israel).

The remaining treatments received the same volume of irrigation without the addition of HA.

No leachates were produced following this addition.

The [+P] treatment was supplemented with 10 g 20% superphosphate (Ca(H2PO4)2)/pot (ICL, Haifa, Israel) at the transition to the flowering photoperiod and every 3 weeks thereafter.

The fertilization solution of the [+NPK] treatment was supplemented with 15% higher concentrations of N, P, and K than the control treatment, added as:

KNO3,
NH4NO3, and
H3PO4

to the final concentrations of 75, 20, and 104 ppm N, P, and K, respectively.

Fertigation was managed in an open cycle.

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Below are some other articles of hers on cannabis (Google Scholar). I combed through many of her articles and others when I was looking to standardize my micronutrient recipe.

Once they publish, hopefully, they will include what you are looking for.

Below is just a screenshot, the list continues beyond these.

Yeah I get that. What I'm saying is they are doing experiments in just one element at a time without disclosing what ANY other element levels were. While testing Nitrogen... again.. what were the P, K, and Mg levels?

 

[Tomatoesonly]

Thank you for that. I also forgot to mention that Humic Acid finding.. that is wild!!

 

[G.O. Joe]

Here's the gist of what her experiments proved.

That series of papers proved nothing except how a specific nute performed when mixed with a particular weird concentration of everything else, which varied with each paper. Another self-promoter seeking consult cash? Nothing approaching your mix was ever applied to the plants, unique cultivars perhaps adapted for saline conditions. It's a far more salty mix than I'd consider for home hydro - preferring not to go over 700 ppm with RO water - but probably not out of line with commercial farming.

 

[Home-Grown]

`

 

[Dr.Mantis]

Dr. Mantis:

I'm sailing in unchartered waters so when I reply I could be comparing my oranges to your apples.

I have a worksheet (template) I am still putting together. I'll post it so that my math is a tad clearer (maybe). : )

View attachment 18833840

Hey thanks for sharing. On your EDTA worksheet you have your transition metal micros under molar mass as "Fe = 55.85 g/mol (heptahydrate)", for example. Is that number the calculated amount of iron per mol of the selected salt?

To me its easier to just divide the target mass of the salt by the molecular weight to give moles, check stoichiometry, apply correction factor.

So for FeSO4 x7H20: 278.01g/mol
Na2EDTA: 292.24g/mol
Desired reaction FeSO4 + Na2(EDTA) --> [(FeEDTA)Na2)] SO4

1. Hydrobuddy says you need 2.394g of FeSO4 x7H20
2. So, (2.394g/278.01g/mol) = .008611 mol of ferrous sulfate
3. Apply 25% correction factor. .008611mol x 1.25 = .01076mol
4. .01076mol x 292.24g/mol = 3.145g of Na2EDTA for 2.394g of FeSO4 hepta hydrate.
5. Repeat for your other salts based on their molecular weights

 

[Tomatoesonly]

Even what I do with GH Flora products is extreme, but it’s kept me growing!

Can you expand on that a bit? Do you have a link to what ya got going on?

 

[Home-Grown]

`

 

[ExNavyInSTL]

That is what I was looking for. Thank you so much. I was just looking at the mass of the Fe portion and not including the Sulfate part. So your listed molar weight makes sense to me.

However, I am not sure if this matters, but on the bottle containing my Disodium EDTA, it says it has a molecular weight of 372.24.

This Disodium EDTA is from HiMedia Labs (India).

If I am to make the change for the new Mol Wt

Should I change out?:

Na2EDTA: 292.24g/mol

to

Na2EDTA: 372.24g/mol

Otherwise, that is the breakdown I was looking for.

You have earned a basket full of good Karma Points. : )

Hey thanks for sharing. On your EDTA worksheet you have your transition metal micros under molar mass as "Fe = 55.85 g/mol (heptahydrate)", for example. Is that number the calculated amount of iron per mol of the selected salt?

To me its easier to just divide the target mass of the salt by the molecular weight to give moles, check stoichiometry, apply correction factor.

So for FeSO4 x7H20: 278.01g/mol
Na2EDTA: 292.24g/mol
Desired reaction FeSO4 + Na2(EDTA) --> [(FeEDTA)Na2)] SO4

1. Hydrobuddy says you need 2.394g of FeSO4 x7H20
2. So, (2.394g/278.01g/mol) = .008611 mol of ferrous sulfate
3. Apply 25% correction factor. .008611mol x 1.25 = .01076mol
4. .01076mol x 292.24g/mol = 3.145g of Na2EDTA for 2.394g of FeSO4 hepta hydrate.
5. Repeat for your other salts based on their molecular weights